along this zone, there is another rock type, volcanic rock. it is serpentinite. it is a very treacherous rock. if you go up market, you will see it where the met -- barack is exposed in that cut. -- for rock that is exposed in that it is cut. it can be hard work and have the consistency of soap and just slides. why is it like that? it is an intrusion. it is like toothpaste that was extruded through a crack in the earth. that means it was a sheer zone or fault, hundreds of millions of years ago, where it actually came up through and bubbled out and formed this band of serpentinite. adjacent to that is this wonderful rock. what is the other thin that is bad about serpentineite? it contains naturally occurring asbestos, which is a carcinogen, known carcinogen. if you go to where st. mary's cathedral is, cathedral hill, that is one of the outcrops. there is a high percentage of serpentinite in the rock. in the old days, the 1930's, 1920's, san franciscans to not bother to deal with the disposal companies. they would take their garbage out the other side of twin peaks,

rock. in the west, the earth is older. more recently volcanic. it tends to be softer. an earthquake in the west, the energy dissipates more in the softer earth. so in the east it's like shaking a rock. if you shake a rock, everything on the rock is going to move, and that's the way it is in the eastern united states. a relatively small earthquake releases a lot of energy over a very large distance. that's what we're seeing today. seeing those shots in washington, d.c., 5.9 earthquake which is a long way away, causing people to go running out of buildings and feel very worried about it. even here in new york where the relative magnitude of the earthquake was under 3 which is thousands of times less thanned actual magnitude of the earthquake. >> yet -- >> reporter: because of the tall buildings people felt this way. >> yes. >> reporter: on the ground floor, i felt it, but very few people felt it. they were on the ground floor of the building. >> indeed. the u.s. geological survey saying the virginia earthquake stuck an area not seismically active? >> caller: turns out ear